Mounting and cathodic protection

ABSTRACT

Methods and apparatus are disclosed. The apparatus includes a substantially cylindrical mount body comprising a first open mouth at a first end of the cylindrical body and a further open mouth at a remaining end of the cylindrical body, a substantially cylindrical inner surface, and an outer surface that includes a plurality of spaced apart substantially parallel recessed regions that extends circumferentially around the body, wherein the cylindrical body is tapered at each end and at least one securing element is located between the recessed regions.

The present application is a divisional of U.S. patent application Ser.No. 16/484,598 filed on Aug. 8, 2019, which is a 371 of PCT ApplicationNo. PCT/GB2018/050681 filed on Mar. 16, 2018 which claims priority to GB1704214.4 filed on Mar. 16, 2017 and GB 1704217.7 filed on Mar. 16,2017. Any and all applications for which a foreign or domestic priorityclaim is identified in the Application Data Sheet as filed with thepresent application are hereby incorporated by reference herein in theirentirety and made a part of this specification.

The present invention relates to a method and apparatus for providingcorrosion protection to a flexible pipe. In particular, but notexclusively, the present invention relates to the provision of one ormore mounting points underneath an outer sheath of a flexible pipe towhich anode elements of a cathodic protection system can subsequently besecured at desired locations remote from a pipe end fitting.

Traditionally flexible pipe is utilised to transport production fluids,such as oil and/or gas and/or water, from one location to another.Flexible pipe is particularly useful in connecting a sub-sea location(which may be deep underwater, say 1000 metres or more) to a sea levellocation. The pipe may have an internal diameter of typically up toaround 0.6 metres (e.g. diameters may range from 0.05 m up to 0.6 m). Aflexible pipe is generally formed as an assembly of flexible pipe bodyand one or more end fittings. The pipe body is typically formed as acombination of layered materials that form a pressure-containingconduit. The pipe structure allows large deflections without causingbending stresses that impair the pipe's functionality over its lifetime.There are different types of flexible pipe such as unbonded flexiblepipe which is manufactured in accordance with API 17J or composite typeflexible pipe or the like. The pipe body is generally built up as acombined structure including polymer layers and/or composite layersand/or metallic layers. For example, pipe body may include polymer andmetal layers, or polymer and composite layers, or polymer, metal andcomposite layers. Layers may be formed from a single piece such as anextruded tube or by helically winding one or more wires at a desiredpitch or by connecting together multiple discrete hoops that arearranged concentrically side-by-side. Depending upon the layers of theflexible pipe used and the type of flexible pipe some of the pipe layersmay be bonded together or remain unbonded.

Some flexible pipe has been used for deep water (less than 3,300 feet(1,005.84 metres)) and ultra-deep water (greater than 3,300 feet)developments. It is the increasing demand for oil which is causingexploration to occur at greater and greater depths (for example inexcess of 8202 feet (2500 metres)) where environmental factors are moreextreme. For example in such deep and ultra-deep water environmentsocean floor temperature increases the risk of production fluids coolingto a temperature that may lead to pipe blockage. In practice flexiblepipe conventionally is designed to perform at operating temperatures of−30° C. to +130° C., and is being developed for even more extremetemperatures. Increased depths also increase the pressure associatedwith the environment in which the flexible pipe must operate. Forexample, a flexible pipe may be required to operate with externalpressures ranging from 0.1 MPa to 30 MPa acting on the pipe. Equally,transporting oil, gas or water may well give rise to high pressuresacting on the flexible pipe from within, for example with internalpressures ranging from zero to 140 MPa from bore fluid acting on thepipe. As a result the need for high levels of performance from certainlayers such as a pipe carcass or a pressure armour or a tensile armourlayer of the flexible pipe body is increased. It is noted for the sakeof completeness that flexible pipe may also be used for shallow waterapplications (for example less than around 500 metres depth) or even forshore (overland) applications.

It is known that an inner fluid retaining layer of a flexible pipe,often referred to as a liner or barrier layer, and an outer fluidretaining layer, referred to as an outer sheath, define between them anannulus region in which various metal structures may be located. Forexample such metal structures are tensile armour windings or pressurearmour windings or the like. Furthermore it is known that if an outersheath of a flexible pipe is breached in use or on installation ingressof seawater into the annulus region can lead to corrosion of themetallic parts. To prevent corrosion cathodic protection has beenutilised. Cathodic protection is a mechanism for providing corrosionprotection and such cathodic protection is well known to those skilledin the art. For example recommended practice DNV-RP-B401 or recommendedpractice DNV-RP-F103 provide guidelines for providing cathodicprotection (CP) systems for submarine pipelines and flexible piperisers. In summary such CP systems rely on the inclusion of metal anodessuch as aluminium or zinc blocks which are less noble and thus have alower reference potential than the metallic regions of a flexible pipewhich are to be protected. At a point of contact where an anode islocated the flexible pipe metals, such as steel windings, will have thepotential of the anode. This potential gradually increases along alength of flexible pipe body away from the anode. The change inpotential is caused by attenuation effects due to the resistance of thestructure of the metal elements as well as other factors.

Because of these well known attenuation effects, and the fact thatanodes used as part of a CP system have conventionally been mounted toend fittings of a flexible pipe, an effective length of flexible pipebody between next adjacent end fittings has been limited. Effectivelymore end fittings have conventionally been utilised than desired inorder to provide anodes, fitted to the end fittings, at a required levelof frequency along a pipeline. This requirement to include “extra” endfittings along a flexible pipe has conventionally increased cost andcomplexity associated with the provision of a subsea pipeline and/orriser.

It is also known that from time to time it is desirable to be able toattach ancillary equipment to a flexible pipe at desired locations alonga length of the flexible pipe on installation or during use. A widevariety of ancillary equipment could in theory be needed. For example,buoyancy modules, bend restrictors, anode clamps, riser clamps,stiffener elements or the like. Conventional techniques for mountingsuch equipment are limited and often rely upon attachment of suchancillary equipment to a rigid end fitting at an end of a pipe.Alternatively certain conventional techniques require complex and costlyand difficult to install securing mechanisms which additionally mayprovide a risk to proper functioning of a flexible pipe.

It is an aim of certain embodiments of the present invention to at leastpartly mitigate the above-mentioned problems.

It is an aim of certain embodiments of the present invention to provideone or more mount points for a CP system along a length of flexible pipebody when that flexible pipe body is manufactured.

It is an aim of certain embodiments of the present invention to providea method and apparatus for enabling one or more anodes to be connectedto a flexible pipe at desired locations remote from the end fitting.

It is an aim of certain embodiments of the present invention to providea mechanism for obviating attenuation effects from a cathodic protectionsystem along a length of flexible pipe.

It is an aim of certain embodiments of the present invention to enablecathodic anodes to be secured to an outer sheath of a flexible pipe atlocations well away from distant end fittings.

It is an aim of certain embodiments of the present invention to enableancillary equipment, such as anode clamps or stiffener elements or bendrestrictor elements or buoyancy modules or riser clamps or a heatermodules or the like, to selectively be secured to flexible pipe body.

It is an aim of certain embodiments of the present invention to providean electrical connection between layers of a flexible pipe which includemetallic components.

It is an aim of certain embodiments of the present invention to providean anti-fretting layer between opposed layers of a flexible pipe whichthus provides a stand off to the opposed layers but which also helpsmaintain metallic parts in the spaced apart layers in electricalconnection.

It is an aim of certain embodiments of the present invention to reduceattenuation effects along a length of flexible pipe body.

According to a first aspect of the present invention there is providedapparatus for mounting a corrosion protection element of a corrosionprotection system to an outer surface region of flexible pipe body,comprising a substantially cylindrical mount body comprising a firstopen mouth at a first end of the cylindrical body and a further openmouth at a remaining end of the cylindrical body, a substantiallycylindrical inner surface, and an outer surface that includes aplurality of spaced apart substantially parallel recessed regions thatextends circumferentially around the body; wherein the cylindrical bodyis tapered at each end and at least one securing element is locatedbetween the recessed regions.

Aptly the inner surface of the mount body has an inner diameter that issubstantially equal to an outer surface diameter provided by an outertensile armour layer of the flexible pipe body.

Aptly a thickness of the body between the inner surface and the outersurface, where the outer surface is not recessed or tapered, is lessthan 1 cm.

Aptly the thickness is less than 0.5 cm.

Aptly the cylindrical body comprises a plurality of body portions, eachbody portion providing a respective section of the cylindrical body.

Aptly each securing element comprises a threaded hole in the cylindricalbody.

Aptly the threaded hole is a blind hole or a through hole.

Aptly the apparatus further comprises a respective circular seal elementlocated in each recessed region.

Aptly at least a region of the cylindrical mount body is electricallyconducted.

Aptly said a region of the cylindrical mount body comprises a whole ofthe mount body.

Aptly said a region is formed from a metallic material.

Aptly the cylindrical mount body comprises an anode mounting collar.

According to a second aspect of the present invention there is provideda method of manufacturing flexible pipe body, comprising steps of:

-   -   providing a tensile armour wire layer by helically winding a        tensile armour wire over an underlying layer;    -   providing at least one substantially cylindrical mount body,        comprising a spaced apart first and further open mouth at        respective ends of the mount body and a substantially        cylindrical inner surface and at least one securing element        between a plurality of spaced apart recessed regions in an outer        surface, over the tensile armour wire layer; and    -   providing an outer sheath over the mount body and the tensile        armour layer.

Aptly the method further comprises providing the mount body over thetensile armour wire layer by locating at least two mating mount bodyportions over the tensile armour wire layer.

Aptly the method further comprises securing the mount body portionstogether to form the substantially cylindrical mount body.

Aptly the method further comprises wrapping a tape layer over and/orunder the tensile armour wire layer and said mount body.

Aptly the method further comprises providing a mark or marks on an outersurface of the outer sheath at a respective location associated with asecuring element of the cylindrical mount body.

Aptly the method further comprises providing the cylindrical mount bodyover the outer surface of the tensile armour layer whereby the mountbody makes an interference fit with the outer surface of the tensilearmour layer.

Aptly the method further comprises providing the mount body in one ormore body portions, at least one body portion comprising a metal region.

Aptly the method further comprises providing the mount body in aplurality of body portions each wholly manufactured from a metallicmaterial.

According to a third aspect of the present invention there is provided amethod of securing an anode to a flexible pipe, comprising the steps of:

-   -   determining a location along a region of flexible pipe body        where a cylindrical mount body, comprising a spaced apart first        and further open mouth at respective ends of the mount body and        a substantially cylindrical inner surface and a plurality of        spaced apart recessed regions in an outer surface, is located;    -   securing an anode or anode clamp element to the mount body by        locating a securing element, located between the recessed        regions, through an outer sheath of the flexible pipe body.

Aptly the method further comprises clamping the anode or anode clampelement to the outer sheath on opposed sides of a location where thesecuring element is located through the outer sheath.

Aptly the method further comprises, via the clamping step, urging outersheath material into the spaced apart recessed regions of thecylindrical mount body, thereby providing a fluid seal on a first andremaining side of the securing element.

Certain embodiments of the present invention provide a convenient to usemounting mechanism which is inbuilt into flexible pipe body as theflexible pipe body is manufactured. Subsequently, as desired, an anodemount and anodes or other such ancillary equipment can be selectivelymounted to the outside of the flexible pipe body at desired locations.

Certain embodiments of the present invention provide an anode mount (orother ancillary equipment or ancillary equipment mount) to which one ormore anode elements can be secured in use and which provides theadditional effect of maintaining integrity of an “anti-birdcage system”.That is to say the mount has an inner surface which is substantiallycylindrical or otherwise profiled to provide support to underlyingtensile armour wire layers. The tensile armour layers where the mount isnot located can be supported via a conventional technique, for exampleby utilising tape windings.

Certain embodiments of the present invention provide a method andapparatus for enabling an anode mount for anodes of a CP system to besecured to flexible pipe body at considerable distances away from anyend fitting. As a result longer lengths of flexible pipe body can beutilised without recourse to a back-to-back end fitting arrangement thanwould otherwise be needed using conventional techniques.

Certain embodiments of the present invention provide a connecting pointfor anodes and an anode mount on a pipe outer sheath without therequirement for a mid-line connection.

Certain embodiments of the present invention provide a mounting pointoutside a tensile layer to make effective contact with a protected area.Aptly the mounting point can provide a sealing surface for an outersheath to maintain outer sheath integrity. Aptly the mounting pointprovides a constraint for the underneath tensile wires to maintainbirdcage performance.

Certain embodiments of the present invention provide a method ofeffectively electrically connecting metallic elements from multiplelayers in flexible pipe body together. As a result resistance along alength of flexible pipe is reduced thus reducing attenuation effects.

Certain embodiments of the present invention provide an anti-frettinglayer that can be used between opposed layer in flexible pipe body andwhich also includes one or more electrically conducting elements whichbridge the space between the separated layers to help provide anelectrical connection at repeated locations along the length of flexiblepipe body.

Certain embodiments of the present invention will now be describedhereinafter, by way of example only, with reference to the accompanyingdrawings in which:

FIG. 1 illustrates flexible pipe body;

FIG. 2 illustrates uses of flexible pipe incorporating the flexible pipebody;

FIG. 3 illustrates a cross section along a length of flexible pipe body;

FIGS. 4A and 4B help illustrate apparatus for mounting a corrosionprotection element over an outer surface of a tensile armour layer;

FIG. 5 illustrates an indicator showing a location of afastening/securing point;

FIG. 6 illustrates an anode clamp secured to the flexible pipe body.

FIG. 7 illustrates a flexible pipe with cathodic protection provided byanodes mounted on an anode mount a great distance from opposed endfittings of the flexible pipe; and

FIG. 8 illustrates an intermediate layer provided by both electronicallyconducting and electrically insulating tapes.

In the drawings like reference numerals refer to like parts.

Throughout this description, reference will be made to a flexible pipe.It is to be appreciated that certain embodiments of the presentinvention are applicable to use with a wide variety of flexible pipe.For example certain embodiments of the present invention can be usedwith respect to flexible pipe and associated end fittings of the typewhich is manufactured according to API 17J. Such flexible pipe is oftenreferred to as unbonded flexible pipe. Other embodiments are associatedwith other types of flexible pipe.

Turning to FIG. 1 it will be understood that the illustrated flexiblepipe is an assembly of a portion of pipe body and one or more endfittings (not shown in FIG. 1 ) in each of which a respective end of thepipe body is terminated. FIG. 1 illustrates how pipe body 100 is formedfrom a combination of layered materials that form a pressure-containingconduit. As noted above although a number of particular layers areillustrated in FIG. 1 , it is to be understood that certain embodimentsof the present invention are broadly applicable to coaxial pipe bodystructures including two or more layers manufactured from a variety ofpossible materials. The pipe body may include one or more layerscomprising composite materials, forming a tubular composite layer. It isto be further noted that the layer thicknesses are shown forillustrative purposes only. As used herein, the term “composite” is usedto broadly refer to a material that is formed from two or more differentmaterials, for example a material formed from a matrix material andreinforcement fibres.

A tubular composite layer is thus a layer having a generally tubularshape formed of composite material. Alternatively a tubular compositelayer is a layer having a generally tubular shape formed from multiplecomponents one or more of which is formed of a composite material. Thelayer or any element of the composite layer may be manufactured via anextrusion, pultrusion or deposition process or, by a winding process inwhich adjacent windings of tape which themselves have a compositestructure are consolidated together with adjacent windings. Thecomposite material, regardless of manufacturing technique used, mayoptionally include a matrix or body of material having a firstcharacteristic in which further elements having different physicalcharacteristics are embedded. That is to say elongate fibres which arealigned to some extent or smaller fibres randomly orientated can be setinto a main body or spheres or other regular or irregular shapedparticles can be embedded in a matrix material, or a combination of morethan one of the above. Aptly the matrix material is a thermoplasticmaterial, aptly the thermoplastic material is polyethylene orpolypropylene or nylon or PVC or PVDF or PFA or PEEK or PTFE or alloysof such materials with reinforcing fibres manufactured from one or moreof glass, ceramic, basalt, carbon, carbon nanotubes, polyester, nylon,aramid, steel, nickel alloy, titanium alloy, aluminium alloy or the likeor fillers manufactured from glass, ceramic, carbon, metals,buckminsterfullerenes, metal silicates, carbides, carbonates, oxides orthe like.

The pipe body 100 illustrated in FIG. 1 includes an internal pressuresheath 110 which acts as a fluid retaining layer and comprises a polymerlayer that ensures internal fluid integrity. The layer provides aboundary for any conveyed fluid. It is to be understood that this layermay itself comprise a number of sub-layers. It will be appreciated thatwhen a carcass layer 120 is utilised the internal pressure sheath isoften referred to by those skilled in the art as a barrier layer. Inoperation without such a carcass (so-called smooth bore operation) theinternal pressure sheath may be referred to as a liner. A barrier layer110 is illustrated in FIG. 1 .

It is noted that a carcass layer 120 is a pressure resistant layer thatprovides an interlocked construction that can be used as the innermostlayer to prevent, totally or partially, collapse of the internalpressure sheath 110 due to pipe decompression, external pressure, andtensile armour pressure and mechanical crushing loads. The carcass is acrush resistant layer. It will be appreciated that certain embodimentsof the present invention are thus applicable to ‘rough bore’applications (with a carcass). Aptly the carcass layer is a metalliclayer. Aptly the carcass layer is formed from stainless steel, corrosionresistant nickel alloy or the like. Aptly the carcass layer is formedfrom a composite, polymer, or other material, or a combination ofmaterials and components. A carcass layer is radially positioned withinthe barrier layer.

A pressure armour layer 130 is a pressure resistant layer that providesa structural layer that increases the resistance of the flexible pipe tointernal and external pressure and mechanical crushing loads. The layeralso structurally supports the internal pressure sheath. Aptly asillustrated in FIG. 1 the pressure armour layer is formed as a tubularlayer. Aptly for unbonded type flexible pipe the pressure armour layerconsists of an interlocked construction of wires with a lay angle closeto 90°. Aptly the lay angle is between 80° and 90° to the axis of thepipe body. Aptly in this case the pressure armour layer is a metalliclayer. Aptly the pressure armour layer is formed from carbon steel,aluminium alloy or the like. Aptly the pressure armour layer is formedfrom a pultruded composite interlocking layer. Aptly the pressure armourlayer is formed from a composite formed by extrusion or pultrusion ordeposition or winding, followed by consolidation. A pressure armourlayer is positioned radially outside an underlying barrier layer.

The flexible pipe body also includes a first tensile armour layer 140and second tensile armour layer 150. Each tensile armour layer is usedto sustain tensile loads and optionally also internal pressure. Aptlyfor some flexible pipes the tensile armour windings are metal (forexample steel, stainless steel or titanium or the like). For somecomposite flexible pipes the tensile armour windings may be polymercomposite tape windings (for example provided with either thermoplastic,for instance nylon, matrix composite or thermoset, for instance epoxy,matrix composite). For unbonded flexible pipe the tensile armour layeris typically formed from a plurality of wires. (To impart strength tothe layer) that are located over an inner layer and are helically woundalong the length of the pipe at a lay angle typically between about 10°to 55°. Aptly the tensile armour layers are counter-wound in pairs.Aptly the tensile armour layers are metallic layers. Aptly the tensilearmour layers are formed from carbon steel, stainless steel, titaniumalloy, aluminium alloy or the like. Aptly the tensile armour layers areformed from a composite, polymer, or other material, or a combination ofmaterials.

Aptly the flexible pipe body includes optional layers of tape 160, 170,180 which help contain underlying layers and to some extent preventabrasion between adjacent layers. The tape layer may optionally be apolymer or composite or a combination of materials, also optionallycomprising a tubular composite layer. Tape layers can be used to helpprevent metal-to-metal contact to help prevent wear. Tape layers overtensile armours can also help prevent “birdcaging”.

The flexible pipe body also includes optional layers of insulationand/or metal winding or polymer layers or tape layers or layersincluding special materials such as optical fibres and an outer sheath190, which comprises a polymer layer used to protect the pipe againstpenetration of seawater and other external environments, corrosion,abrasion and mechanical damage. Any thermal insulation layer helps limitheat loss through the pipe wall to the surrounding environment and maycomprise layers of tape or at least one extruded layer of insulatingmaterial.

Each flexible pipe comprises at least one portion, referred to as asegment or section, of pipe body 100 together with an end fittinglocated at at least one end of the flexible pipe. An end fittingprovides a mechanical device which forms the transition between theflexible pipe body and a connector. The different pipe layers as shown,for example, in FIG. 1 are terminated in the end fitting in such a wayas to transfer the load between the flexible pipe and the connector.

FIG. 2 illustrates a riser assembly 200 suitable for transportingproduction fluid such as oil and/or gas and/or water from a sub-sealocation 221 to a floating facility 222. For example, in FIG. 2 thesub-sea location 221 includes a sub-sea flow line 225. The flexible flowline 225 comprises a flexible pipe, wholly or in part, resting on thesea floor 230 or buried below the sea floor and used in a staticapplication. The floating facility may be provided by a platform and/orbuoy or, as illustrated in FIG. 2 , a ship. The riser assembly 200 isprovided as a flexible riser, that is to say a flexible pipe 240connecting the ship to the sea floor installation. The flexible pipe maybe in segments of flexible pipe body with connecting end fittings.

It will be appreciated that there are different types of riser, as iswell-known by those skilled in the art. Certain embodiments of thepresent invention may be used with any type of riser, such as a freelysuspended (free-hanging, catenary riser), a riser restrained to someextent (buoys, chains), totally restrained riser or enclosed in a tube(I or J tubes). Some, though not all, examples of such configurationscan be found in API 17J. FIG. 2 also illustrates how portions offlexible pipe can be utilised as a jumper 250.

FIG. 3 illustrates a cross section through a short length of theflexible pipe body 100 shown in FIG. 1 in more detail. As shown in FIG.3 a carcass layer 120 supports a barrier layer 110. An inner surface ofthe barrier layer 110 provides the fluid retaining surface which definesa bore region 300 along which transport of production fluids can takeplace. The direction of flow of the production fluid is illustrated byarrow A in FIG. 3 although it will be appreciated that the flexible pipemay be utilised in different directions.

An innermost tape layer 160 is located on a radially outermost surfaceof the pressure armour layer 130 to help support windings of thepressure armour layer. This innermost tape layer 160 also helps provideanti-fretting effects between the inner/underlying pressure armour layer130 and windings of the first tensile armour layer 140. Adjacentwindings 310 _(0,1 . . . m) of tensile armour wire of the first tensilearmour layer are illustrated in FIG. 3 . The innermost tape layer 160 isan intermediate layer between a pressure armour layer 130 and an innertensile armour layer 140.

A further tape layer 170 is an intermediate layer between the firsttensile armour layer 140 and the second tensile armour 150. Adjacentwindings 320 _(0,1 . . . n) of the second tensile armour wire providethe outer tensile armour layer 150.

A further tape layer 180 is wound outside the second tensile armourlayer 150. This helps provide support and anti-birdcaging effects to thetensile armour layer/s. The outer sheath 190 is formed outside the outertape layer 180. This further tape layer 180 is an intermediate layerbetween the outer tensile armour layer (and mount body) and an overlyinglayer.

Also illustrated in FIG. 3 is a substantially cylindrical mount body 350which is provided over the outermost tensile armour layer 150. Aradially innermost surface 360 of the mount body 350 is substantiallycylindrical and smooth (it could alternatively be selectively profiled)and has an inner dimension sized to provide an interference fit with theouter surface of the windings 320 _(0,1 . . . n) of the radiallyoutermost tensile armour layer 150. The mount body 350 has a taperedfirst end 365 at a downstream end of the mount body 350 and a furthertapered end 370 spaced apart from the first end at an upstream end ofthe mount body. It will be appreciated that the mount body 350 may beprovided in either orientation (facing an expected flow or facing withthe flow).

A radially outermost surface 380 of the mount body is provided andincludes the radially outer surface of the two tapered ends 365, 370, asubstantially cylindrical central region 385 and a first recessed region390 at a downstream end of the mount body 350 and a further recessedregion 395 at an upstream end of the mount body.

FIGS. 4A and 4B help illustrate the mount body 350 located over theouter surface of the outermost tensile armour layer 150 duringmanufacture of flexible pipe body. As illustrated in FIG. 4A the mountbody 350 is a substantially cylindrical member which has a first openmouth at a first end of the cylindrical body and further open mouth at aremaining end of the cylindrical body. As illustrated in FIG. 4A themount body is provided in two substantially C-shaped body parts 400,410. When the two C-shaped parts are put together a ring-like orbracelet-like member is formed. The multiple portions of the body can beplaced together subsequent to the outer tensile armour layer 150 beingmanufactured and secured in place. Aptly the C-shaped (or other shaped)parts are screwed together or secured via self adhesive tape.Alternatively the mount body may be a single integral piece slid alongthe tensile armour layer or alternatively may be formed from more thantwo mount body portions.

Also shown in FIGS. 4A and 4B is a blind hole 420 in one of the mountbody parts 400. This is a threaded hole which has an end terminatingwithin the body of the first portion 400 of the mount body 350. Asimilar blind hole 430 may optionally be provided in the remaining mountbody part 410. Each threaded blind hole provides a securing elementwhich is useable subsequent to completion of the manufacture of theflexible pipe body to enable ancillary equipment such as an anode clamp,stiffener element or buoyancy module or the like to be secured to theflexible pipe body prior to installation or subsequent to installation.It will be appreciated that the threaded hole could be a threadedthroughhole or other securing mechanism that mates with another securingelement of the ancillary equipment in use.

FIG. 4 also helps illustrate how the spaced apart recessed regions 390,395 of the mount body each provide a substantially cylindrical outersurface. The two thus provided surfaces are spaced apart andsubstantially parallel. More than two spaced apart recessed regionscould optionally be utilised. FIG. 4B helps illustrate how the innersurface of the mount body can be smooth.

The mount body 350 illustrated in FIG. 4 has a thickness of about around0.7 cm in the central region between the spaced apart recesses 390, 395.Aptly as an alternative the mount body has a thickness of between 5 and20 mm. Aptly the thickness is about around 10 mm.

The mount body 350 has a thickness which makes the mount body rigidenough to not deform in use. Furthermore the thickness is sufficientlythick taking into account the material used to enable any ancillaryequipment to be secured to the mount body in use. Aptly the mount bodyportions are each formed from a common material. Aptly the mount bodyportions are manufactured from possible materials include, but are notlimited to, steel, iron, copper, aluminium, titanium, magnesium, zincalloy and/or other electrically conductive materials. Carbon fibrecomposite or other composite materials that are electrically conductivecould also be utilised.

The mount body 350 shown has an axial length of around 70 to 150 mm.Aptly the axial length is around 100 mm.

It will be appreciated that the mount body 350 is located over theoutermost tensile armour layer 150 during manufacture of the flexiblepipe body. Thereafter an outer “anti-birdcaging” tape layer 180 can bewound over the outer surface of the tensile armour layer 150 and overthe mount body 350. Alternatively the tape layer may beterminated/started on either side of the mount body 350. The mount bodymay also comprise one or more teeth or other clamping elements forclamping onto the edges of a terminated tape layer 180. This helpssecure the tape/s in the tape layer as well as achieving a goodconductive contact with the armour layer 150. Thereafter the outersheath 190 and any optional intervening further layers, such asinsulating layers, can be formed.

FIG. 5 helps illustrate a region of the flexible pipe body where thebracelet-like mount body is located under the outer sheath 190. Theouter surface of the pipe body is shown swollen in an exaggerated way inthe Figure to help understanding. FIG. 5 helps illustrate how anindicator 500 can be provided on an outer surface 510 of the outersheath to help provide subsequent users with a guide as to a location ofeach securing element of the mount body. It will be appreciated that awide variety of indictors could be utilised. For example a single markmay be made or multiple marks giving guidance as to the securing elementlocation can be utilised. The mark or marks may optionally be coloured.A circled cross is shown in FIG. 5 . Aptly the indicator is a stampedregion in the outer surface 510 of the outer sheath 190. It will beappreciated that if the bracelet-like mount body includes multiplefastening points then an indicator for each fastening point may beprovided. Alternatively a single indicator can be provided providing asubsequent user knows of a distribution scheme for each fastening pointof the mount body so they only need to identify one valid position

It will be appreciated that whilst the mount body shown in FIGS. 3 and 4are shown at a single location along a length of flexible pipe bodymultiple similar mount bodies each separated from one another by acommon or optionally different distance may be provided at selectedlocations along a length of flexible pipe body as it is manufactured.Thereafter when the flexible pipe body, as part of a flexible pipe, isinstalled at a work site as a flow line or riser or the like ancillaryequipment such as an anode clamp can be secured to the outside of theflexible pipe using one or more of the mount bodies. As a result a veryconvenient mounting mechanism is inbuilt into flexible pipe body at thepoint of manufacture for subsequent optional use. The securing processcan be permanent or replaceable in the sense that ancillary equipmentmay be permanently fastened to the mount body or may be fastened andthen removed and replaced by other ancillary equipment includingoptionally a sealing “blank”.

FIG. 6 illustrates the mounting point provided by the mount body 350shown in FIGS. 3 and 4 in more detail but with ancillary equipment inthe form of an anode clamp, useable as a mount for anode elements,secured to the mount body. As illustrated in FIG. 6 in order to securethe anode clamp 600 to the mount body 350 an aperture 610 is cut at alocation identified by the indicator 500. The aperture 610 has a sizedetermined by a size of the anode clamp 600 to be secured to the mountbody. It will be appreciated that whilst the ancillary equipment shownin FIG. 6 as an anode clamp should be in electrical connection to themount body, different types of ancillary equipment may optionally beconnected to the mount body without forming an overlarge aperture in theouter sheath. Rather a body part of the ancillary equipment may merelybe urged against an outer surface 510 of the outer sheath and then oneor more securing elements such as bolts selected to mate with thesecuring element 420 in a mount body can be driven through the outersheath. For example the ancillary equipment may be secured using boltswhich pass through small apertures made in the outer sheath and screwedinto the threaded blind hole 420 of the mount body. Metal bolts thusprovide an electrical connection between the mount body and the anodeclamp. The outer sheath in such circumstances can act as a stand off.Additional sealing O-rings or the like may be utilised between theancillary equipment and the outer sheath to help provide a seal aroundthe aperture/s. This helps prevent seawater ingress into the annulus ofthe pipe body.

Turning again to FIG. 6 the aperture 610 is cut through the outer sheathto have a size and shape configured to coincide with a size and shape ofthe anode clamp 600. The aperture is made not only through the outersheath but also through the outer tape layer 180. Alternatively if theouter tape layer 180 includes electrically conducting elements (seediscussion later) the anode clamp 600 may rest on an outer surface ofthat tape layer.

FIG. 6 helps illustrate how a downstream clip 620 and an upstream clip630 may be wrapped around the outer sheath and tightened to drive theouter sheath material and tape layer into respective recessed regions390, 395. Each clip 620, 630 is a ring like element which can betightened to consolidate outer sheath material and tape layer materialinto a respective recess. As a result a liquid tight seal can beprovided on adjacent sides of the anode clamp to help prevent ingress ofseawater into the annulus region provided between an inner surface ofthe outer sheath and a radially outer surface of the barrier layer. Therecessed regions 390, 395 may also comprise a saw-tooth or similarprofile in order to help sealing against the outer sheath material.

FIG. 6 helps illustrate how a bolt 640 can be located in a recess 650 inthe anode clamp 600 and can be driven to secure into the blind threadedhole 420 in the mount body thus securing the anode clamp 600 to themount body. It will be appreciated that multiple bolts distributedaround the circumference of the anode clamp could be utilised. Thesecuring process draws the anode clamp into close contact with the mountbody.

In the case of the ancillary equipment being an anode clamp, aspreviously discussed, the anode clamp 600 makes an electrical connectionto the metallic mount body 350, or optionally to just at least a regionof the mount body that is electrically conductive, and through the mountbody to the outermost tensile armour windings. As a result cathodicprotection can be provided to the outer most tensile amour wire windingsby attaching anode blocks to the anode clamp 600. If each intermediatetape layer is electrically conductive (see later) the anode blocks arethus electrically connected to many metal layers.

FIG. 7 helps illustrate a flexible pipe which includes a segment offlexible pipe body 100 with a first end fitting 710 at a firstrespective end of the flexible pipe body and a further end fitting 720at a remaining end of the flexible pipe body. The flexible pipe shown inFIG. 7 is an elongate structure which can in practice have a length ofmany kilometres between the end fittings. Anode blocks 730 areillustrated secured circumferentially around the anode clamp 600. Asillustrated in FIG. 7 the location of the anode blocks 730 is shown aconsiderable distance away from any end fitting. It will be appreciatedthat end fittings could additionally or optionally utilise anode blocksin addition to the anode blocks 730 and anode clamps 600 and mountingmechanism previously described. The anode clamp 600 and anode block 730can thus be provided distal to (or indeed proximate to if desired) anyend fitting. Aptly the mount points and anode clamps are more than 2kilometres from any end fitting. Aptly the anode blocks and associatedmount are more than one kilometre from any end fitting. Aptly thedistances p and d shown in FIG. 7 are both greater than 1 km. Thedistances p and d can be the same or different.

FIG. 7 also helps illustrate how a conventional anode clamp 740 may besecured to an end fitting 720 and multiple anode blocks 750 (three shownin FIG. 7 secured via the clamp to the end fitting. Such an anode clamp740 and anodes 750 provide CP to a region proximate to the end of theflexible pipe body near the end fitting 720. It will be appreciated thatif desired similar anode clamps and anode blocks could optionally beadditionally secured to the remaining end fitting 710.

Cathodic protection can thus be provided to a flexible pipe via anodeelements mounted to end fittings and/or to anode elements secured in amid-line location but without needing back-to-back end fittings.

FIG. 8 helps illustrate an intermediate tape layer 170 in more detail.It will be appreciated that the further intermediate tape layers 160,180 could be similarly provided. As illustrated in FIG. 8 the tape layeris a relatively thin layer formed by winding thin, long, substantiallyflat, strips helically around an underlying layer. Optionally theelongate strips of tape can be an electrically insulating material andare used to provide anti-fretting properties (preventing adjacentmetallic layers from rubbing against each other). Alternatively, asillustrated in FIG. 8 , an intermediate tape layer can be formed bywinding two different strips each having different characteristics. InFIG. 8 an electrically insulating tape formed by polypropylene or thelike is wound over an underlying layer (in the example shown in FIG. 8over the innermost tensile armour layer 140). The tape is thin andflexible so that adjacent windings 800 _(0,1 . . . 4) of tape overlapand curve. Windings 810 _(0,1 . . . 4) of a further strip-like tape areillustrated in FIG. 8 . These are formed from a metallic material suchas steel or the like. Other electrically conducting materials such as,but not limited to, copper, aluminium, nickel, gold or silver foil ortapes comprising alloys of these or comprising other conductivematerials such as graphene or the like could optionally be utilised. Theelectrically insulating windings and electrically conductive windingsare interposed. In this way the tape layer provides a combination ofcheap and flexible anti-fretting characteristics together with anelectrically conductive pathway which electrically connects anunderlying layer such as a metallic underlayer with an overlying layersuch as a metallic overlayer (for example a first tensile armour layer140 can be electrically connected to a second tensile armour layer 150).As a result the windings of an overlying layer and the windings of anunderlying layer are electrically interconnected via an intermediatelayer. As a result a net electrical resistance offered by any metalliclayer which extends along a length of the flexible pipe body is reduced.As a result attenuation effects otherwise expected with CP systems aresignificantly reduced. As a result a frequency of anode elements thatare needed along a length of flexible body is reduced relative toconventional techniques.

An intermediate tape layer which includes electrically conductingelements and electrically insulating elements enables a variety ofmaterials to be used and makes use of material characteristics to thebest of those materials ability. For example electrically insulatingmaterials can be utilised which provide superior anti-fretting and/orsupport capabilities. Additionally a material that is highlyelectrically conductive can be utilised and distributed as a windingthroughout the intermediate layer to provide a bridge forming anelectrical connection between otherwise spaced apart layers. Byelectrically connecting opposed layers together an electrical resistanceper unit length of the flexible pipe body is much reduced relative toconventional techniques and thus attenuation effects can be reduced. Asa result anode elements are needed less frequently along a length offlexible pipe body than would otherwise be needed according toconventional techniques to provide a desired level of cathodicprotection. It will be appreciated that whilst the intermediate layershown in FIG. 8 includes an electrically insulating tape wound adjacentto, and sequentially alternating with, an electrically conductive tapeit is possible according to certain embodiments of the present inventionto utilise multiple insulating tape windings with a single electricallyinsulating tape winding or vice versa depending upon desire.

Aptly the tapes are wound helically around an underlying layer using awinding station that rotates with one or more sources of tape feedingthe insulating tape/s and electrically conducting tape/s to respectivetouchdown points. Those touchdown points enable each continuous elongatetape to be simultaneously wound albeit at offset positionscircumferentially and/or longitudinally. In this way immediately nextwindings of a different tape can have a 0-90% overlap with animmediately preceding winding (which may be of the same or differenttape type). Aptly there is at least a partial overlap of the tapewindings.

Throughout the description and claims of this specification, the words“comprise” and “contain” and variations of them mean “including but notlimited to” and they are not intended to (and do not) exclude othermoieties, additives, components, integers or steps. Throughout thedescription and claims of this specification, the singular encompassesthe plural unless the context otherwise requires. In particular, wherethe indefinite article is used, the specification is to be understood ascontemplating plurality as well as singularity, unless the contextrequires otherwise.

Features, integers, characteristics or groups described in conjunctionwith a particular aspect, embodiment or example of the invention are tobe understood to be applicable to any other aspect, embodiment orexample described herein unless incompatible therewith. All of thefeatures disclosed in this specification (including any accompanyingclaims, abstract and drawings), and/or all of the steps of any method orprocess so disclosed, may be combined in any combination, exceptcombinations where at least some of the features and/or steps aremutually exclusive. The invention is not restricted to any details ofany foregoing embodiments. The invention extends to any novel one, ornovel combination, of the features disclosed in this specification(including any accompanying claims, abstract and drawings), or to anynovel one, or any novel combination, of the steps of any method orprocess so disclosed.

The reader's attention is directed to all papers and documents which arefiled concurrently with or previous to this specification in connectionwith this application and which are open to public inspection with thisspecification, and the contents of all such papers and documents areincorporated herein by reference.

1. Apparatus for mounting a corrosion protection element of a corrosionprotection system to an outer surface region of flexible pipe body,comprising: a substantially cylindrical mount body comprising a firstopen mouth at a first end of the cylindrical body and a further openmouth at a remaining end of the cylindrical body, a substantiallycylindrical inner surface, and an outer surface that includes aplurality of spaced apart substantially parallel recessed regions thatextend circumferentially around the body; wherein the cylindrical bodyis tapered at each end and at least one securing element is locatedbetween the recessed regions.
 2. The apparatus as claimed in claim 1,further comprising: the inner surface of the mount body has an innerdiameter that is substantially equal to an outer surface diameterprovided by an outer tensile armour layer of the flexible pipe body. 3.The apparatus as claimed in claim 1, further comprising: a thickness ofthe body between the inner surface and the outer surface, where theouter surface is not recessed or tapered, is less than 1 cm.
 4. Theapparatus as claimed in claim 3 wherein the thickness is less than 0.5cm.
 5. The apparatus as claimed in claim 1, further comprising: thecylindrical body comprises a plurality of body portions, each bodyportion providing a respective section of the cylindrical body.
 6. Theapparatus as claimed in claim 1, further comprising: each securingelement comprises a threaded hole in the cylindrical body.
 7. Theapparatus as claimed in claim 6 wherein the threaded hole is a blindhole or a through hole.
 8. The apparatus as claimed in claim 1, furthercomprising: a respective circular seal element located in each recessedregion.
 9. The apparatus as claimed in claim 1 wherein at least a regionof the cylindrical mount body is electrically conductive.
 10. Theapparatus as claimed in claim 9 wherein said a region of the cylindricalmount body comprises a whole of the mount body.
 11. The apparatus asclaimed in claim 10 wherein said a region is formed from a metallicmaterial.
 12. The apparatus as claimed in claim 1 wherein thecylindrical mount body comprises an anode mounting collar.
 13. Theapparatus as claimed in claim 1 wherein the apparatus is for securing ananode or anode clamp to the outer surface region of a portion offlexible pipe body, and said at least one securing element is forsecuring an anode or anode clamp.
 14. A method of securing an anode to aflexible pipe, comprising the steps of: determining a location along aregion of flexible pipe body where a cylindrical mount body, comprisinga spaced apart first and further open mouth at respective ends of themount body and a substantially cylindrical inner surface and a pluralityof spaced apart recessed regions in an outer surface, is located; andsecuring an anode or anode clamp element to the mount body by locating asecuring element, located between the recessed regions, through an outersheath of the flexible pipe body.
 15. The method as claimed in claim 14,further comprising: clamping the anode or anode clamp element to theouter sheath on opposed sides of a location where the securing elementis located through the outer sheath.
 16. The method as claimed in claim15, further comprising: via the clamping step, urging outer sheathmaterial into the spaced apart recessed regions of the cylindrical mountbody, thereby providing a fluid seal on a first and remaining side ofthe securing element.
 17. The method as claimed in claim 14, wherein themethod is a method of securing an anode to a portion of flexible pipebody via a mount body.
 18. A method of manufacturing flexible pipe body,comprising steps of: providing a tensile armour wire layer by helicallywinding a tensile armour wire over an underlying layer; providing atleast one substantially cylindrical mount body, comprising a spacedapart first and further open mouth at respective ends of the mount bodyand a substantially cylindrical inner surface and at least one securingelement between a plurality of spaced apart recessed regions in an outersurface, over the tensile armour wire layer; and providing an outersheath over the mount body and the tensile armour layer.